1. Field of the Invention
This invention relates to a structural assembly of the type used for the production of foundry molds from a granular material in a substantially automated fashion wherein the process of charging the mold box assembly and associated pattern sections, hardening the granular charge into a predetermined configuration and dimension, removal of the formed foundry product and unused granular portion and entire recycling of the set forth operation is accomplished.
2. Description of the Prior Art
The original process for producing shell cores and molds was developed by Dr. Johannes Croning in Germany during World War II. Dr Croning's process was directed to the use of thermal setting resins and producing a fluidized hardenable synthetic resin mixture. To date the Croning process is used but has serious drawbacks due to the fact that the resin utilized results in a hardening of the binder under the action of heat in the range of 400.degree. F. to 480.degree. F. To create such heat large amounts of natural gas are used in foundries employing the Croning process. In addition the subject Croning process necessitates the construction of core boxes of high heat resistence. Such core box structures are obviously subject to relatively short life cycles.
Other disadvantages associated with the Croning process include undesirable working conditions as well as significantly long curing times. These long curing times result in low productivity. Example of such curing times are three minutes for a ten pound core.
In order to overcome the obvious disadvantages associated with the Croning process other foundry processes have been developed for producing cores and/or molds. Such process is known as the "cold box" process first generally demonstrated in 1968. Such process involved the coating of a sand or granular material with a binder and then curing the binder coated sand by passing a catalyst gas through the sand mixture once the sand is disposed into its predetermined configuration due to formation with a pattern structure.
One major disadvantage associated with the cold box process involves the relatively greater weight of the produced core or mold caused by the entire volume defined within the pattern of the mold box being filled with sand and hardened by exposure to the catalyst gas. Such weight was generally in the range of three to four times heavier than comparably sized shell cores or molds. This obviously resulted in waste of material, increased production costs and product handling problems.
However, more recently a method of manufacturing shell molds utilizing the "cold box" process was developed by Dunlop as disclosed in U.S. Pat. No. 4,089,363. According to Dunlop a shell type mold can be formed by creating a distinct pressure differential within a mold box or gasing chamber through introduction of catalyst gas after exposure of binder coated sand to a working surface of a vented pattern. While the Dunlop process clearly eliminates the problems previously associated with "cold box" processes due to excess weight, Dunlop still uses manually oriented procedures and does not show or describe a technique readily adaptable to mass production of molds. In Dunlop it would appear that the working surface of the resulting mold does not exactly correspond to the precisely configured working surface of the pattern and therefore is questionable practical application.